Transmission and reception of a broadcast signal based on IP has been extended in a digital broadcast system. In particular, significance of an IP-based broadcast signal transmission/reception environment has been emphasized in mobile digital broadcasting such as digital video broadcasting (DVB)-next generation handheld (NGH), a European broadcast standard, or advanced television systems committee (ATSC)-mobile handheld (MH), a North American broadcast standard. In addition, a hybrid broadcast system serviced through a linkage between a broadcast network and an Internet network is expected to be constructed in a next generation broadcast system.
IP which is mainly used in the Internet network has been developed for transmission of general-purpose data rather than broadcasting. Thus, a technology needs to be additionally developed to use IP in a broadcast system.
In general, a network configuration is expressed by protocol layers. For example, the network configuration may have a hierarchical structure based on an open systems interconnection (OSI) reference model. The OSI reference model includes seven layers. However, in a digital broadcast system based on IP, layer 5 and up may have an integrated function or have indistinguishable functions. For example, in the IP-based digital broadcast system, layers lower than or equal to layer 4 may transmit broadcast data. Therefore, even though a method and an apparatus for processing signaling data described in the present application may correspond to a layer defined in seven OSI layers, the method and the apparatus are applicable to a network configuration of N layers newly defined in the IP-based digital broadcast system.
Meanwhile, in the broadcast system, signaling data is included in a broadcast signal and transmitted such that a viewer easily acquires a desired broadcast service, broadcast program, broadcast channel, broadcast event, etc. from a receiver. The signaling data (or signaling information) includes a series of information necessary for the receiver to rapidly access a transmission parameter, broadcast system information, program specific information (PSI), a program and service information protocol (PSIP), DVB-service information (SI), a service signaling channel, the broadcast service, etc.
In general, a broadcast receiver receives broadcast signals in real time and processes the received broadcast signals, and thus a delay may occur in broadcast signal processing. The delay needs to be avoided. However, in the IP-based digital broadcast system, broadcast data needs to be processed according to a protocol corresponding to each layer and transmitted/received. Thus, signaling data included in a particular layer may be used by the receiver when the signaling data is parsed up to the corresponding layer.
Meanwhile, a user of the receiver frequently changes a broadcast service, a broadcast channel, etc. and thus the receiver needs to be able to promptly change channels. In this process, the receiver needs to acquire signaling data included in a particular layer in order to search for a broadcast service, a broadcast channel, etc. selected by the viewer. In order to acquire the signaling data included in the particular layer, the receiver needs to process data of lower layers up to the corresponding layer. Therefore, there is a problem of processing data of several layers each time the viewer makes a selection.